The ratio of gravitational force and electrostatic repulsive force between two electrons is approximately (gravitational constant $=6.7\times {10}^{-11} {\mathrm{Nm}}^2 {\mathrm{kg}}^{-2}$, mass of an electron $=9.1\times {10}^{-31} \mathrm{kg}$, charge on an electron $=1.6\times {10}^{-19} \mathrm{C}$)